As a semiconductor non-volatile memory for data storage, NOR flash memory or NAND flash memory is typically used. In these semiconductor non-volatile memories, large capacity is realized by miniaturization of a memory device and a drive transistor. However, limit of the miniaturization is pointed out because a large voltage is necessary for writing and erasing and the number of electrons injected into a floating gate is restricted.
A variable resistance memory such as resistance random access memory (ReRAM) and phase-change random access memory (PRAM) has been currently proposed as a next-generation non-volatile memory that may exceed limit of miniaturization (for example, see PTL 1 and NPL 1). Each of these memories has a simple structure including a resistance change layer between two electrodes. It is considered that atoms or ions are moved by heat or an electric field to form a conduction path, and thus a resistance value of a resistance change layer is varied to perform writing and erasing. Specifically, a memory device that uses a transition metal element, a chalcogen element, and copper (Cu) easily causing ion conduction has been disclosed (for example, see PTL 2).
As described above, examples of a method of achieving large capacity in a memory performing writing and erasing with use of resistance variation include miniaturization of a memory described above.